1. Field of the Invention
The present invention relates generally to data communications and, more specifically, to a method and apparatus to perform persistence tests in a network, such as, for example, a wireless communication network.
2. Background
The explosive increase in demand for wireless connectivity has created numerous challenges, one of which revolves around potential interference among multiple users trying to access and share common communication channels. In wireless communication networks, such as, for example, cellular telephone networks, one or more mobile user stations, which may be mobile or stationary, communicate with one or more base stations arranged to provide coverage to the mobile stations. Each mobile station transmits and receives voice or data or both through the base stations. The mobile station needs to establish an active traffic channel connection with one or more base stations during the connection setup phase. Alternatively, the mobile station may attempt to establish such a network access connection during the registration process or during data bursts for short messaging service (SMS).
During the connection setup state, for example, the mobile station performs a network access attempt characterized by one or more access sub-attempts. Each access sub-attempt includes one or more transmissions called access probes. The access probes are grouped into one or more access probe sequences. The timing of the access probes and access probe sequences is expressed in terms of access slots. The transmission of an access probe begins usually at the start of an access slot. For each access slot, the mobile station performs a persistence test, as described in “Medium Access Control (MAC) Standard for cdma2000 Spread Spectrum Systems,” Release D, by the Third Generation Partnership Project 2 (3GPP2), 3GPP2 C.S0003-D, version 1.0, of Feb. 13, 2004. If the test is successful, the first access probe of the access probe sequence starts in that particular access slot. Otherwise, if the test is unsuccessful, the access probe sequence is deferred until at least the next access slot and the mobile station has to wait in an idle mode until the next access slot triggers a new persistence test.
However, for shorter access slots, such as, for example, access slots around 1.25 milliseconds, the repeated performance of unsuccessful persistence tests, followed each time by a subsequent idle waiting of the mobile station, burdens the usage of the central processing unit (CPU) of the mobile station and has the potential to block the performance of other CPU tasks. In addition, for longer access slots, such as, for example, access slots in the range of 80 to 520 milliseconds, the repeated performance of unsuccessful persistence tests, followed by the subsequent idle waiting of the mobile station, leads to increased power consumption. Thus, what is needed is a method and apparatus to perform persistence tests that increase the task processing efficiency of the CPU within the mobile station and lead to reduced power consumption.